MEATS AS TROUT FOOD 129 



The early mortality mentioned above can often bo checked by 

 proi^er fee(lin<j:. Our experience has shown that the following prac- 

 tice is very satisfactory in producing rapid growth with low mortal- 

 ity: For the first 3 or 4 weeks the young fingerlings are fed beef 

 heart exclusively. This meat can be ground into very fine particles 

 with little waste. After the fourth week the food need not be ground 

 so fine and 50 per cent of beef liver can be added to the ration. This 

 provides the fingerlings with larger particles of a very nutritious 

 food which can be ased less wastefully than when the fish are smaller. 

 The continued use of beef heart in the ration tends to lower the 

 mortality. 



BEEF MELTS 



Beef melts or spleen is one of the cheapest meats available to fish 

 culturists. In our experiments fingerling and yearling brook trout 

 were fed this meat straight and in combinations with dry products. 

 (Figs. 10 and 11.) In practically all cases very poor growth resulted, 

 although the accompanying mortality was rather low. Any instance 

 in which a ration containing beef melts gave good results w^as directly 

 traceable to some other constituent in the ration. We must conclude, 

 therefore, that despite any advantage in price the poor growth made 

 by trout on this diet is alone sufficient reason for not including it 

 among the suitable hatchery meats. 



PIG LIVER 



Pig liver is another staple meat which has been used extensively. 

 As a food for both brook and rainboAv fingerlings it has proved infe- 

 rior to beef liver, particularly in regard to growth. (Fig. 10.) The 

 exceptional stickiness of ground pig liver is an objectionable feature 

 when it is fed to fingerlings in hatchery troughs, since it materially 

 increases the labor involved in keeping troughs and screens in a clean 

 and sanitary condition. 



Pig liver, when fed straight or in combination with other foods, 

 has made an excellent showing Avith yearling trout. (Fig. 11.) It is 

 especially adapted for use with dry products, since it makes an ideal 

 binding medium and will permit the use of quite fine meals which are 

 difficult to feed without a great deal of waste unless held together by 

 some sticky material. 



The addition of 50 per cent beef heart to the pig-liver ration of 

 brook-trout fingerlings resulted in added growth and a lowering of 

 the mortality. No advantage from this combination was noted with 

 rainbow fingerlings. Yearling brook trout fed on this meat mixture 

 gave no evidence that the ration was superior to pig liver alone. 



SHEEP LIVER 



Considering its popularity at many hatcheries our results with 

 sheep liver have been disappointing. " With brook fingerlings (fig. 

 1) the mortality was very high and the growth unsatisfactory in 

 comparison with fish fed on beef liver or beef heart. Consequently, 

 we liave made no attempt to feed sheep liver to young brook trout 

 in our later experiments. 

 105086°— 30 2 



